<meta charset="utf-8">
(#) Mismatched view type

!!! ERROR: Mismatched view type
   This is an error.

Id
:   `WrongViewCast`
Summary
:   Mismatched view type
Severity
:   Error
Category
:   Correctness
Platform
:   Android
Vendor
:   Android Open Source Project
Feedback
:   https://issuetracker.google.com/issues/new?component=192708
Since
:   Initial
Affects
:   Kotlin and Java files and resource files
Editing
:   This check runs on the fly in the IDE editor
Implementation
:   [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/ViewTypeDetector.kt)
Tests
:   [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/ViewTypeDetectorTest.kt)
Copyright Year
:   2011

Keeps track of the view types associated with ids and if it finds a
usage of the id in the Java code it ensures that it is treated as the
same type.

!!! Tip
   This lint check has an associated quickfix available in the IDE.

(##) Example

Here is an example of lint warnings produced by this check:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text
src/test/pkg/WrongCastActivity.java:13:Error: Unexpected cast to
ToggleButton: layout tag was Button [WrongViewCast]
    ToggleButton toggleButton = (ToggleButton) findViewById(R.id.button);
                                ----------------------------------------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here are the relevant source files:

`res/layout/casts.xml`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~xml linenumbers
&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" &gt;

    &lt;view class="Button"
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button" /&gt;

    &lt;EditText
        android:id="@+id/edittext"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="EditText" /&gt;

    &lt;view
        android:id="@+id/view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" /&gt;

&lt;/LinearLayout&gt;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

`src/test/pkg/WrongCastActivity.java`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~java linenumbers
package test.pkg;

import android.app.Activity;
import android.os.Bundle;
import android.widget.*;

public class WrongCastActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.casts);
        Button button = (Button) findViewById(R.id.button);
        ToggleButton toggleButton = (ToggleButton) findViewById(R.id.button);
        TextView textView = (TextView) findViewById(R.id.edittext);
    }
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can also visit the
[source code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/ViewTypeDetectorTest.kt)
for the unit tests for this check to see additional scenarios.

The above example was automatically extracted from the first unit test
found for this lint check, `ViewTypeDetector.testBasic1`.
To report a problem with this extracted sample, visit
https://issuetracker.google.com/issues/new?component=192708.

(##) Suppressing

You can suppress false positives using one of the following mechanisms:

* Using a special `lint.xml` file in the source tree which turns off
  the check in that folder and any sub folder. A simple file might look
  like this:
  ```xml
  &lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;lint&gt;
      &lt;issue id="WrongViewCast" severity="ignore" /&gt;
  &lt;/lint&gt;
  ```
  Instead of `ignore` you can also change the severity here, for
  example from `error` to `warning`. You can find additional
  documentation on how to filter issues by path, regular expression and
  so on
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html).

* In Gradle projects, using the DSL syntax to configure lint. For
  example, you can use something like
  ```gradle
  lintOptions {
      disable 'WrongViewCast'
  }
  ```
  In Android projects this should be nested inside an `android { }`
  block.

* For manual invocations of `lint`, using the `--ignore` flag:
  ```
  $ lint --ignore WrongViewCast ...`
  ```

* Last, but not least, using baselines, as discussed
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).

<!-- Markdeep: --><style class="fallback">body{visibility:hidden;white-space:pre;font-family:monospace}</style><script src="markdeep.min.js" charset="utf-8"></script><script src="https://morgan3d.github.io/markdeep/latest/markdeep.min.js" charset="utf-8"></script><script>window.alreadyProcessedMarkdeep||(document.body.style.visibility="visible")</script>